Amgen on Wednesday projected revenue for 2013 that exceeds Wall Street estimates and said it was on track to deliver on its 2015 forecasts well ahead of schedule.

The world's largest biotechnology company forecast 2013 revenue of $17.8 billion to $18.2 billion and adjusted earnings of $6.85 to $7.15 per share. Analysts on average are looking for revenue of $17.7 billion and earnings of $6.99 per share, according to Thomson Reuters I/B/E/S.

The 2013 forecast suggests "that they expect good momentum from 2012," RBC Capital Markets analyst Michael Yee said. "They have a history of guiding conservatively and then beating."

The company was true to that history on a call with analysts and investors.

Amgen previously targeted 2015 revenue of $16 billion to $18 billion and adjusted earnings of $7.25 to $8.60 per share. On Wednesday, Amgen management said it was on track to hit the upper end of its 2015 revenue guidance two years early and the EPS forecast at least one year early.

It said it is on track to earn at least $8 per share for 2015.

Amgen, whose shares gained 34% last year, noted that its deferred 2012 research and development (R&D) tax credit, which the U.S. Congress failed to address in time for 2012, would be recorded in the first quarter of 2013. The company also intends to continue to return cash to investors through meaningful increases to its dividend going forward.

Net profit for the fourth quarter fell as sales of some key products declined and R&D spending and other costs jumped.

Excluding items, Amgen had adjusted earnings of $1.40 per share, topping analysts' average expectations by 2 cents. Net profit fell to $788 million, or $1.01 per share, from $934 million, or $1.08 per share, a year ago.

Revenue for the quarter rose 11% to $4.42 billion, edging past Wall Street estimates of $4.37 billion. But R&D spending rose 9% due to large clinical trials of two experimental drugs, including for a promising cholesterol fighter from a new class of medicines called PCSK9 inhibitors that is just beginning expensive late stage testing.

Selling, general and administrative costs rose 13% for the quarter.

Sales of Enbrel for rheumatoid arthritis and psoriasis jumped 23% to $1.16 billion with the help of price increases. That topped analyst estimates of $1.08 billion.

But sales of other important products declined and fell short of expectations, including combined worldwide sales of white blood cell boosters Neupogen and Neulasta, which fell 1% to $1.3 billion.

Sales of anemia drugs Aranesp and Epogen, which have been declining in recent years because of safety concerns and usage restrictions continued to slide, but at a slower pace.

Aranesp sales fell % to $489 million, while the older red blood cell booster, Epogen, fell just 1% to $479 million, both missing analysts' expectations of about $505 million and $480 million, respectively.

Sales of newer drug Xgeva to prevent fractures due to cancer that has spread to the bones rose to $215 million from $201 million in the prior quarter, but fell short of Wall Street estimates of about $222 million.

The related osteoporosis drug, Prolia, exceeded expectations of about $137 million with fourth quarter sales of $154 million.

"Enbrel and Prolia were the only major line-items that appeared to beat," Mark Schoenebaum, an analyst with ISI Group, said in a research note.

"Neupogen/Neulasta missed by a bit, and this needs to be monitored as Amgen prepares for more U.S competition from Teva in late 2013," Schoenebaum said.